If an overstretched rubber band could talk, it would use this voice. The tense voice has no give, it's full of anxiety, and sounds as if it could shatter at any moment.
When a character speaks in a tense voice, the tension emits from the audio to the audience, and we all feel it. The type A's we know have it, the pefectionaists and the ones who have trouble relaxing may have tension in their voice when they speak. The tense voice can show these characteristics in someone, whether it's a character in an audiobook, commercial, or voiceover in a film.
When you want you to use a tense voice, it's often to portray a character. This can be anything from a commerical or audiobook. You probably don't want this voice for your podcasts and motivational voiceovers. The tense voice shares not only the character's feelings in the moment, but it's a great way to showcase this personality. A tense voice does much more than speak, it shows the inner workings of what makes a character tick and can be very effective when used in the right place.
A tense voice is tight. Speech may be hurried and clipped. You won't hear jovial, soothing tones. A tense voice can also be laced with worry and anxiety; it just can't relax. Though it can be of any tone or pitch, it often may head to the higher pitched side.
We all know tension, and when a character speaks in a tense voice, we get it. It's great for showing growth or problem solving, along with the personality of your characters.